I added USB Network card, but it gave me only 100Mb/Full Duplex. After that, I realized that card was 10/100, so I decided to buy a new one.

I purchased new USB Network card with speed 10/100/1000. When I connected it, the speed is still 100Mb/Full Duplex. It is connected to the 1Gb NIC on my server and I know that it should give me 1Gb/Full Duplex.